The New York State Assembly on Wednesday approved a measure that allows the New York City Board of Elections to replace state-of-the art optical scanning voting machines around the city with decades-old mechanical-lever machines for the city's mayoral primary in September.

The State Senate is considering a similar proposal, but has not yet approved it.

If it does, the mechanical-lever machines, purchased by the city in the 1960s, will be taken out of storage and redeployed in all five boroughs.

The decision to use the old lever machines instead of newer optical scanners, which the city spent $95 million on a few years ago, apparently has to do with timing, according to The New York Times.

The primary election is slated for Sept. 10. If no candidate gets 40% of the votes, the city will hold a runoff election two weeks later, on Sept. 24.

According to the Times, city election officials are concerned about the practicality of using optical scan voting machines given the short gap between the primary and runoff election.

With optical scan systems, voters mark their choices on a pre-printed paper ballot sheet and feed it into the machine that then scans and records the ballot. The machines maintain a paper trail that can be used to manually verify results in close elections.

According to election officials, it takes much more time to manually count results from the optical scanners, and to reset the machines, than it does with the old lever machines. The city's Board of Elections has said that in order to use optical scan voting machines without a hitch, they would need at least 60 days between the primary and the runoff elections.

The city will bring back the optical scanners for the general elections in November and all other elections in future.

A spokeswoman for the NYC Board of Elections did not respond to requests for comment.

The possible return of the mechanical machines, and the justifications for their use, had some election watchdogs scratching their heads in puzzlement.

"Basically, this has more to do with a dysfunctional New York City Elections Board than any real need to return to lever machines," said Bo Lipari, founder of New Yorkers for Verified Voting, a group that keeps an eye on election integrity issues. "The current scanners are quite capable of handling the possible run-off elections, and the State Board of Elections has even submitted a plan for doing so to the New York City Board."

Using the lever machines would again segregate disabled voters, and allow them to be identified because they will be the only voters who have paper ballots, he said. The city's planned use of the mechanical-lever machines also would appear to be in violation of state and federal laws mandating the retirement of these machines.

"They need to address a lot of issues to make elections work in New York City, but bringing back lever machines is not one of them," Lipari said.

Pamela Smith, president of election watchdog group Verified Voting, claimed that mechanical-lever machines are less secure than an optically scanned paper ballot system.

"With a ballot scanner system, the process of capturing and reporting the totals is automated, and you also have a way to go back and check it," she said. Election officials can check to see that vote totals were transcribed correctly and whether the totals actually reflect voters' intent, Smith said.

"With a paper ballot system, you can conduct a recount of each record of voter intent." This kind of auditing is not possible with the older machines, which have been shown in the past to be vulnerable to undetectable tampering, Smith argued.

"If the lever machines fail to keep a record of each vote cast, you have nothing to fall back upon, the way you do with a paper ballot based system," she said. New York has had issues with recount processes in the past. But the focus should be on addressing those issues rather than resorting to old voting technology, she said.

A spokesman for Election Systems & Software (ES&S), the vendor of the optical scanning systems, expressed surprise at the city's decision. In comments to the Times, a spokesman for the company said the city had rejected a suggestion of buying high-speed vote counters to deal with the time crunch cited by election officials.